08f5b5c35ece28a8bae48569a6ded550ae396449  [JSC] WASM debugger: unencodable instance-id sentinel, clearer predicate names, and a loud failure when the server cannot start

Classified as not security-relevant.
Triage note: Renames hasDebugger()->isConnected() and isDebuggerReady()->hasSentLibraryList() across the ENABLE(WEBASSEMBLY_DEBUGGER) GDB-stub code, reorders a RELEASE_ASSERT in registerInstance, and adds an INVALID_ID sentinel assert. Pure debugger-tooling refactor behind a build flag, not attacker-reachable.
This commit was flagged by the signal scorer and reviewed by AI (not a human). It is listed only so the triage is auditable; there is no root-cause analysis because this is not a vulnerability fix.

Structural signals: security_assert (+6.47), clamp_saturate (+1.8), msg_soft (+1.0), msg_noise (-2.5), area:Source/JavaScriptCore/runtime (+2.5)